M Linden called live music in Second Life a "killer ap." I was on that theme in an article a while back:
Music is real business in virtual reality
That article included a prospective scenario about Joe the Geek and his biworld beer party. He invited a bunch of his friends to sit around his 96 inch TV screen and sing along with EvaMoon Ember. I even suggested an inworld monetizing scenario:
"…an entrepreneur might decide that there is a potential demand for a new service, Party Special, set up specifically for entertaining guests at a party. With specific guests getting recognition and comment. Chatting with performers on break. Requesting specific songs. All the things that add value to a performance at a night club. And things that might make the host want to pay extra for a private party."
That entrepreneur, Party Marty, would be offering (and charging for) an inworld catering service. Turn-key operation. You tell Marty what you need: